1. Field of the Invention
The present invention relates to the field of technology pertaining to caps for protecting valved discharge openings of pressurized fluid cylinders during handling and transporting of the cylinders. More specifically, the invention relates to an improved safety cap assembly for attachment to the existing threaded cap ring flange of a pressurized cylinder.
2. Description of the Prior Art
Conventional metal cylinders for containing certain fluids, such as oxygen and flammable gases, under highly pressurized conditions are provided with some form of cap means for enclosing and protecting the valved discharge opening of the cylinder from being accidentally ruptured when the cylinder is handled and transported. Because the fluid contained within the cylinder is highly pressurized and often flammable, accidental rupturing of the cylinder valve from severe impact poses a serious potential for physical injury to personnel and property damage. Because of this situation, minimum industrial safety standards have been established for such caps in order to assure their reliability under anticipated normal conditions of use. Typically, such caps are formed of steel in order to withstand the constant impacting and rough handling to which they are normally subjected during handling and transporting of the cylinders.
It is well known to provide safety caps for pressurized cylinders in the form of a dome-shaped cap member having a threaded internal wall portion which permits the cap to be threadedly engaged onto a existing threaded cap ring flange secured to a pressurized cylinder. Attachment and removal of a cap having a threaded coupling of this type is time consuming. Moreover, the threaded engagement often rusts and corrodes, particularly when the cylinders are used in corrosive environments. A threaded coupling may also become distorted in the event the cap is subjected to a severe impact, thereby making the cap very difficult to remove from the cylinder. Under such circumstances, it is not uncommon for an operator to attempt to release a cap having a corroded or distorted threaded coupling by striking the cap, thereby further posing the danger of rupturing the valve of the discharge opening.
In order to overcome the aforementioned problems with a threaded coupling for the safety cap of a pressurized cylinder, there have been many attempts to provide alternative forms of coupling mechanisms wherein the cap may be detachably secured to the cylinder without requiring a direct threaded engagement between the cap and cylinder. For example, it is known to provide a mechanism in the form of ring which is first threadedly engaged onto the existing cap ring flange of the cylinder and thereafter detachably engage the cap to the ring through a correspondingly configured interlock between the cap and ring. The use of tabs, latches and bayonet type couplings between the cap and a portion of the cylinder are also well known. However, though mechanisms of this type do overcome the inherent problems associated with threaded couplings, they nevertheless do have other disadvantages. For example, nonthreaded coupling mechanisms are often quite complex and expensive to manufacture. They are also difficult to manipulate and often do not provide absolute security against accidental dislodgment of the cap during normal use.